a, 20 . x - 3 = 0
=> x - 3 = 0 : 20
=> x - 3 = 0
=> x = 0 + 3
=> x = 3
b, ( x - 1 ) . ( x - 2 ) = 0
TH 1 :
x-1 = 0
=> x = 0 + 1
=> x = 1
TH2 :
x - 2 = 0
=> x = 0 + 2
=> x = 2
Vậy x = 1 hoặc x = 2
1)20.\(x-3=0\)
\(20.x=0+3\)
\(20.x=3\)
\(x=3:20\)
\(x=\frac{3}{20}\)
Vậy \(x=\frac{3}{20}\)
2)\(\left(x-1\right).\left(x-2\right)=0\)
\(\Rightarrow\)\(x-1=0\) hoặc \(x-2=0\)
TH1:\(x-1=0\)
\(x=0+1\)
\(x=1\)
TH2:\(x-2=0\)
\(x=0+2\)
\(x=2\)
Vậy \(x=1\) hoặc \(x=2\)